WASHINGTON — The head of the Drug Enforcement Administration is refusing to support a bill backed by the Obama administration that would lower the length of mandatory minimum sentences for federal drug crimes, putting her at odds with her boss Attorney General Eric Holder on one of the criminal justice reform initiatives he hopes to make a centerpiece of his legacy.

During testimony before the Senate Judiciary Committee last week, Sen. Chuck Grassley (R-Iowa) asked DEA Administrator Michele Leonhart about the role of mandatory minimums in drug cases. Grassley cited the opposition among some law enforcement groups to the Smarter Sentencing Act, a bipartisan bill that would reduce the length of mandatory minimum sentences for some drug crimes.

“Having been in law enforcement as an agent for 33 years, [and] a Baltimore City police officer before that, I can tell you that for me and for the agents that work for DEA, mandatory minimums have been very important to our investigations,” Leonhart said. “We depend on those as a way to ensure that the right sentences are going to the … level of violator we are going after.”